JP5679816B2 - Adhesives and binders for use in electro-optic assemblies - Google Patents

Description

  The present invention relates to International Publication No. WO2003 / 104888 pamphlet, WO2004 / 023195 pamphlet, WO2005 / 041160 pamphlet, WO2005 / 07377 pamphlet, and WO2007 / 104003 pamphlet, and international application. Related to the numbers PCT / US2006 / 60049 and PCT / US2006 / 62399. The reader refers to these international applications for background information related to the present invention.

  The present invention relates to electro-optic assemblies useful in the manufacture of electro-optic displays, and adhesives and binders for use of such assemblies. More specifically, the present invention provides adhesive and binder compositions with controlled volume resistance, as well as electro-optic assemblies and displays that incorporate such adhesives. The present invention is specifically, but not exclusively, intended for use with displays that include encapsulated electrophoretic media. However, the present invention describes various other types of electro-optics in which the medium is solid in the sense that it can have an internal cavity that often contains a fluid (liquid or gas), but has a solid external surface. Media can also be used. Thus, the term “solid electro-optic display” includes capsule electrophoretic displays, capsule liquid crystal displays, and other types of displays discussed below. The adhesive disclosed herein may be useful for applications other than electro-optic displays.

  Background terminology and state of the art for electro-optic displays are discussed in detail in US Pat. No. 7,012,600, to which the reader is referred for further information. Therefore, this term and the state of the art are briefly summarized below.

  The term “electro-optic” as applied to a material or display, as used herein, is a material having a first display state and a second display state that differ in at least one optical property, wherein an electric field is applied to the material. Used in its conventional sense in imaging technology to refer to a material that, when applied, changes from its first display state to its second display state. Some electro-optic materials are solid in the sense that the material can have an internal liquid or gas-filled space and often has a solid external surface. Such a display using a solid electro-optic material may hereinafter be referred to as a “solid electro-optic display” for convenience. Thus, the term “solid electro-optic display” includes rotating bichromal member displays, capsule electrophoretic displays, microcell electrophoretic displays and capsule liquid crystal displays.

  The terms “bistable” and “bistable” are used herein to refer to a display comprising display components having a first display state and a second display state that differ in at least one optical characteristic. Used in their conventional sense in the technical field, therefore any given component assumes a finite duration addressing pulse assuming its first display state or second display state. When the addressing pulse ends after being driven by a), the state remains at least for several times, for example at least four times the minimum duration of the addressing pulse required to change the state of the display element. continue.

Some types of electro-optic displays, for example:
(A) rotating bichromal member display (eg, US Pat. Nos. 5,808,783; 5,777,782; 5,760,761; 6,054) No. 071, No. 6,055,091; No. 6,097,531; No. 6,128,124; No. 6,137,467; No. 6,147,791);
(B) Electrochromic display (eg O'Regan, B. et al., Nature 1991, 353, 737; Wood, D., Information Display, 18 (3), 24 (March 2002) Bach, U. et al., Adv. Mater., 2002, 14 (11), 845; US 6,301,038; 6,870,657; (See 6,950,220);
(C) Electrowetting display (Hayes, RA, et al., “Video-Speed Electronic Paper Based on Electronics”, Nature 425, 383-385 (September 25, 2003) and US Patent Application Publication No. 2005/0151709));
(D) Particle-based electrophoretic display (where a plurality of charged particles move through a fluid under the influence of an electric field) (US Pat. No. 5,930,026; US Pat. No. 5,961,804) No. 6,017,584; No. 6,067,185; No. 6,118,426; No. 6,120,588; No. 6 No. 6,124,851; No. 6,130,773; and No. 6,130,774; US Patent Application Publication No. 2002/0060321. No. 2002/0090980; No. 2003/0011560; No. 2003/0102858; No. 2003/0151702; No. 2003/0222315 No. 2004/0014265; No. 2004/0075634; No. 2004/0094422; No. 2004/0105036; No. 2005/0062714; and 2005/0270261; and WO 00/38000 pamphlet; WO 00/36560 pamphlet; WO 00/67110 pamphlet; and WO 01/079161 pamphlet; and European Patent 1, See U.S. Patent Nos. 099,207 B1; 1,145,072 B1; and other MIT and E Ink patents and applications discussed in the aforementioned US Pat. No. 7,012,600. about)
Is known.

  There are several different variations of electrophoretic media. The electrophoretic medium can be a liquid or gaseous fluid; for gaseous fluids, see, for example, Kitamura, T .; Et al, "Electrical toner movement for electronic paper-like display", IDW Japan, 2001, paper HCS1-1, and Yamaguchi, Y. et al. "Toner display using insulating particles charged triboelectrically", IDW Japan, 2001, paper AMD4-4; US Patent Application Publication No. 2005/0001810; European Patent Application No. 1,462,847; No. 1,482,354; No. 1,484,635; No. 1,500,971; No. 1,501,194; No. 1,536,271 No. 1,542,067; No. 1,577,702; No. 1,577,703; and No. 1,598,694; and International Published Application WO 2004/090626 Pamphlet; WO 2004/0794 2 pamphlet; and see the first WO2004 / 001498 pamphlet. These media can be encapsulated, including a number of small capsules, each of which is itself an internal phase containing electrophoretic mobile particles suspended within a liquid suspension medium, and within that Includes a capsule wall surrounding the phase. Usually, the capsules themselves are held in a polymer binder to form a coherent layer positioned between the two electrodes; see the aforementioned MIT and E Ink patents and applications. Alternatively, the walls surrounding the discrete microcapsules in the encapsulated electrophoretic medium can be replaced by a continuous phase, thus creating a so-called polymer dispersed electrophoretic display, where the electrophoretic medium is Including a plurality of discrete droplets of electrophoretic fluid and a continuous phase of polymeric material; see, for example, US Pat. No. 6,866,760. In this application, such polymer-dispersed electrophoretic media are considered subspecies of encapsulated electrophoretic media. Another variation is the so-called “microcell electrophoretic display”, in which charged particles and fluid are held in a plurality of cavities formed in a carrier medium, usually a polymer film; See 6,672,912 and 6,788,449.

  Electrophoretic media are often opaque (eg, in many electrophoretic media, the particles substantially block the transmission of visible light through the display) and operate in reflective mode, but many electrophoretic displays Can be operated in a so-called "shutter mode" where one display state is substantially opaque and one is light transmissive. For example, the aforementioned US Pat. Nos. 6,130,774 and 6,172,798 and US Pat. No. 5,872,552; US Pat. No. 6,144,361 See US Pat. No. 6,271,823; US Pat. No. 6,225,971; and US Pat. No. 6,184,856. A dielectrophoretic display that is similar to an electrophoretic display, but that relies on variations in electric field strength, can operate in a similar mode; see US Pat. No. 4,418,346. Other types of electro-optic displays can also be operated in shutter mode.

  Capsule electrophoretic displays typically do not suffer from the failure modes of clustering and settling of traditional electrophoretic devices, and the ability to print or coat the display on a wide variety of flexible and rigid substrates Give additional benefits such as. (The use of the term “printing” is intended to include all forms of printing and coatings, including pre-metering coatings such as patch dye coatings, slot or extrusion coatings, slide or cascade coatings, curtain coatings; roll coatings; For example, knife over roll coating, front and back roll coating; gravure coating; dip coating; spray coating; meniscus coating; spin coating; brush coating; air knife coating; silk screen printing process; electrostatic printing process; Treatment; electrophoretic deposition (see US Pat. No. 7,339,715); and other similar techniques, including but not limited to. Thus, the resulting display can be flexible. Furthermore, since the display medium can be printed (using various methods), the display itself can be made inexpensively.

  Other types of electro-optic media, such as polymer dispersed liquid crystals, can also be used in the display of the present invention.

  Electro-optic displays typically comprise an electro-optic material layer and at least two other layers disposed on opposite sides of the electro-optic material, one of these two layers being an electrode layer. In most such displays, both of the layers are electrode layers, and one or both of the electrode layers are patterned to define the pixels of the display. For example, one electrode layer can be patterned into elongated row electrodes and the other can be patterned into elongated column electrodes that are orthogonal to the row electrodes, wherein a pixel is defined by the intersection of the row and column electrodes. Or more generally, one electrode layer has the form of a single continuous electrode, and the other electrode layer is patterned into a matrix of pixel electrodes, each of which is a pixel of the display Is defined. In another type of electro-optic display intended for use with a stylus, printhead or similar movable electrode (separate from the display), only one of the layers adjacent to the electro-optic layer comprises an electrode, The layer on the opposite side of the layer is usually a protective layer intended to prevent the movable electrode from damaging the electro-optic layer.

  The manufacture of a three-layer electro-optic display typically includes at least one lamination operation. For example, in some of the aforementioned MIT and E Ink patents and applications, an encapsulated electrophoretic medium comprising capsules in a binder is used on an indium tin oxide (ITO) or similar conductive coating ( Capsules that are coated on a flexible substrate that functions as one electrode of the final display and that the capsule / binder coating is dried to form a coherent layer of electrophoretic medium that is firmly adhered to the substrate A method of manufacturing a type electrophoretic display is described. Separately, a backplane is prepared that includes an array of pixel electrodes and a suitable arrangement of conductors that connect the pixel electrodes to a drive circuit. To form the final display, a substrate having a capsule / binder layer thereon is laminated to the backplane using a lamination adhesive. (Very similar processing replaces the backplane with a simple protective layer, for example an electrophoretic display that can be used with a stylus or similar movable electrode by a plastic film over which the stylus or other movable electrode can slide. Can be used to prepare). In one preferred form of such processing, the backplane is itself flexible and is prepared by printing pixel electrodes and conductors on a plastic film or other flexible substrate. An obvious lamination technique for mass production of displays by this process is roll lamination using a laminating adhesive. Similar manufacturing techniques can be used for other types of electro-optic displays.

  As discussed in the aforementioned US Pat. No. 6,982,178 (see column 3, lines 63-5, line 46), many components used in solid-state electro-optic displays, and this The methods used to manufacture such displays are derived from the technology used in liquid crystal displays (LCDs). However, the methods used to assemble LCDs cannot be used for solid state electro-optic displays. LCDs typically form a backplane and front electrode on separate glass substrates, then these components are glued together, leaving a small gap between them, and the resulting assembly is placed under vacuum And assembling the assembly in a liquid crystal bath so that the liquid crystal flows through the gap between the backplane and the front electrode. Finally, the liquid crystal is put in place and the gap is sealed to obtain the final display.

  This LCD assembly process cannot be easily transferred to a solid state electro-optic display. Since the electro-optic material is a solid, it must exist between the backplane and the front electrode before these two integers are secured together. Furthermore, in contrast to liquid crystal materials that are simply placed between the front electrode and the backplane without being bonded to either, solid electro-optic media usually need to be fixed to both; The electro-optic medium is formed on the front electrode (since this is generally easier than forming the medium on a circuit-containing backplane), and then usually the entire surface of the electro-optic medium is covered with an adhesive, By stacking under heat, pressure, and possibly under vacuum, the front electrode / electro-optic medium combination is stacked on the backplane. Thus, most prior art methods for final lamination of solid electrophoretic displays are essentially batch methods in which (usually) electro-optic media, lamination adhesive and backplane are brought together just before final assembly. It is desirable to provide a method that is better suited for mass production.

  US Pat. No. 6,982,178 describes a method for assembling a solid state electro-optic display (including a capsule electrophoretic display) that is well suited for mass production. In essence, this patent includes, in turn, a so-called “front plane” comprising a light transmissive conductive layer; a solid electro-optic medium layer in electrical contact with the conductive layer; an adhesive layer; and a release sheet. Laminate (front plane laminate ("FPL")) is described. Typically, the light transmissive conductive layer is placed on a light transmissive substrate, which can be manually wound around a 10 inch (254 mm) diameter drum without permanent deformation of the substrate. In the sense that it can be made, it is preferably flexible. The term “light transmissive” is used in this patent and in this specification to refer to an electro-optic medium (which is usually a conductive material) through which a layer designated in this way transmits enough light to view through that layer. Used to mean that changes in the display state of the layer and the adjacent substrate (if present) can be observed; if the electro-optic medium displays a change in the reflectance of invisible light Thus, the term “light transmissive” should, of course, be construed to refer to the transmission of the associated invisible light.

  US Pat. No. 6,982,178 also describes a method for testing an electro-optic medium in a front plane laminate prior to incorporation of the front plane laminate into a display. In this test method, the release sheet includes a conductive layer, and a voltage sufficient to change the optical state of the electro-optic medium is applied between the conductive layer and the conductive layer on the opposite side of the electro-optic medium. Applied. The observation of the electro-optic medium then reveals any defects in the medium, so laminating the defective electro-optic medium into the display results in discarding the entire display, not just a bad front plane laminate As well as the costs incurred.

  US Pat. No. 6,982,178 describes a second method for testing an electro-optic medium in a front plane laminate by charging on a release sheet and thus forming an image on the electro-optic medium. Is also described. This image is then observed as before to detect any defects in the electro-optic medium.

  An assembly of electro-optic media using such a front plane laminate removes the release sheet from the front plane laminate and contacts the adhesive layer and backplane under conditions effective to bond the backplane to the adhesive layer. Thereby fixing the adhesive layer, the electro-optic medium layer and the conductive layer to the backplane. Because the front plane laminate can be mass-produced, usually using roll-to-roll coating technology, and then cut into pieces of any size required for use by a particular backplane, this process is Well adapted to production.

  US 2004/155857 discloses a so-called “double release sheet” which is an essentially simplified version of the aforementioned front plane laminate of US Pat. No. 6,982,178. Have been described. One form of double release sheet comprises a layer of solid electro-optic medium sandwiched between two adhesive layers, one or both of which is covered with a release sheet. Another form of double release sheet comprises a layer of solid electro-optic medium sandwiched between two release sheets. Two separate laminations; typically, in the first lamination, the double release sheet is laminated to the front electrode to form the front subassembly, and then in the second lamination, the front subassembly is Both forms of the double release film, except that lamination is included on the backplane to form the final display (although the order of these two laminations can be reversed if necessary) is included. Intended for use in processes for assembling electro-optic displays from the previously described front plane laminates and generally similar processes.

  The aforementioned 2007/0109219 describes a so-called “inverted front plane laminate” which is a modification of the front plane laminate described in the aforementioned US Pat. No. 6,982,178. The inverted front plane laminate comprises, in order, at least one light transmissive protective layer and a light transmissive conductive layer; an adhesive layer; a solid electro-optic medium layer; and a release sheet. This inverted front plane laminate is used to form an electro-optic display having a layer of lamination adhesive between the electro-optic layer and the front electrode or front substrate; a second, usually thin layer of adhesive is It may or may not exist between the electro-optic layer and the backplane. Such an electro-optic display can have both good resolution and good low-temperature performance.

  As discussed in the aforementioned U.S. Pat. Nos. 7,012,735 and 7,173,752, in electro-optic displays (or used to make such electro-optic displays). The choice of lamination adhesive for use (in front plane laminates, inverted front plane laminates, double release sheets or other subassemblies) presents certain specific problems. Since the lamination adhesive is usually positioned between the electrodes that apply the electric field required to change the electrical state of the electro-optic medium, the electrical properties of the adhesive are usually important. Lamination adhesives also need to meet several mechanical and rheological criteria, including adhesive strength, flexibility, ability to withstand and flow at lamination temperatures. The number of commercially available adhesives that can meet all relevant electrical and mechanical standards is small, and in practice the most suitable lamination adhesives are some polyurethanes, such as US Patent Application Publication No. 2005/2005. No. 0107564. These polyurethanes include tetramethylxylene diisocyanate (TMXDI-system name 1,3-bis (1-isocyanato-1-methylethyl) -benzene), polypropylene glycol, and 2,2 chain-extended with hexamethylenediamine. -Based on polymerization with bis (hydroxymethyl) propionic acid. After the polyurethane is prepared, it is dispersed as an aqueous latex-like suspension by neutralization with triethylamine and dilution with water. In practice, however, the conductivity of polyurethane cannot be changed by controlling the proportion of materials used in its manufacture.

  As a result, polyurethane adhesives are not sufficiently conductive for use in many electro-optic displays and electro-optic assemblies, and the aforementioned US Pat. Nos. 7,012,735 and 7,173,752 are mentioned. It is known to increase its conductivity by doping it with a salt or other material, as described in the specification. A preferred dopant for this purpose is tetrabutylammonium hexafluorophosphate (hereinafter “TBAHFP”). Unfortunately, it has been found that adhesives formulated in this way can damage active matrix backplanes comprising transistors made from certain organic semiconductors.

  The present invention provides an alternative form of lamination adhesive that can reduce or eliminate the problems caused by prior art adhesives when used in displays containing organic semiconductors. The present invention also extends to the modification of binders used in electro-optic displays to reduce or eliminate problems caused by prior art binders in displays containing organic semiconductors.

  The present invention has two main aspects. The first aspect relates to the incorporation of ionic material into the adhesive layer in such a way that the material does not diffuse out of the adhesive layer. The second aspect relates to pretreatment of adhesive materials or binders to remove certain diffusive species that can damage organic semiconductors.

  Accordingly, in one aspect, the present invention provides an electro-optic assembly comprising an adhesive layer and an electro-optic material layer, the adhesive layer comprising a polymer adhesive material and an ionic material, the ionic material comprising One of its cations and anions immobilized on the polymer adhesive material and the other of its cations and anions freely moving through the polymer adhesive material, the ionic material comprising the polymer adhesive material An electro-optic assembly is provided that reduces the volume resistivity of the polymer adhesive and is not removed by heating the polymeric adhesive material to about 50 ° C.

  For convenience, the cation or anion of the ionic material that is fixed to the polymer adhesive material is referred to as “fixed ion”, and the cation or anion that is free to move through the polymer adhesive material is referred to as “mobile ion”. . Usually, the fixed ions are chemically bonded to the polymer adhesive, and various techniques for obtaining such ions bonded to the polyurethane adhesive are discussed below. However, such a chemical bond is not absolutely necessary, provided that the fixed ions cannot move through the polymer adhesive; for example, the fixed ions are different from the polymer adhesive, but the chains are entangled with it. Part of the polymer can be formed.

  In one form of electro-optic assembly, the ionic material comprises a quaternary ammonium or phosphonium cation and a carboxylate anion fixed to a polymeric adhesive material. The polymeric adhesive material can include polyurethane. Alternatively, the ionic material may comprise a quaternary ammonium or phosphonium cation immobilized on a polymeric adhesive material and a hexafluorophosphate, tetrabutyl borate or tetraphenyl borate anion. In another form of the electro-optic assembly, the ionic material is selected from the group comprising repeating units derived from basic monomers and sulfonates, sulfates, hexafluorophosphates, tetrafluoroborate, bis (methanesulfonyl) imidates, phosphates and phosphonates. Containing mobile anions. Basic monomers include, for example, vinyl pyridine, β-dimethylaminoethyl acrylate, N-methyl or benzyl (vinyl pyridine), N-alkyl or alkaryl-N′-vinyl imidazole, and β- (trimethylammonio). Any one or more of ethyl) acrylate or methacrylate may be included.

  In such an electro-optic assembly, the electro-optic material can include a rotating bichromal member or an electrochromic material. Alternatively, the electro-optic material can include an electrophoretic material that includes a plurality of charged particles disposed in a fluid and can move through the fluid under the influence of an electric field. Charged particles and fluids can be confined within multiple capsules or microcells. Alternatively, the charged particles and fluid may exist as a plurality of discrete droplets surrounded by a continuous phase comprising a polymeric material. This fluid may be a liquid or a gas.

  The invention extends to an electro-optic display, front plane laminate, reverse front plane laminate or double release film comprising the electro-optic assembly of the invention.

  The present invention also provides an electro-optic assembly comprising an adhesive layer and an electro-optic material layer, wherein the adhesive layer is dialyzed or diafiltered to remove organic species having a molecular weight of less than about 3,500. An electro-optic assembly is provided that includes a polymer adhesive material that has been subjected to a process.

  The invention also provides an electro-optic assembly comprising an adhesive layer and an electro-optic material layer, wherein the adhesive layer does not exceed about 500 ppm based on the total weight of the adhesive layer and the electro-optic material layer. An electro-optic assembly is provided that includes a polymeric adhesive material having a methylpyrrolidone content.

  In such an electro-optic assembly, the polymeric adhesive material can include polyurethane. The N-methylpyrrolidone content preferably does not exceed about 200 ppm, and desirably 100 ppm, based on the total weight of the adhesive layer and electro-optic material layer.

  In such an electro-optic assembly, the electro-optic material can include a rotating bichromal member or an electrochromic material. Alternatively, the electro-optic material can include an electrophoretic material that is disposed in a fluid and includes a plurality of charged particles that can move through the fluid under the influence of an electric field. Charged particles and fluids can be confined within multiple capsules or microcells. Alternatively, the charged particles and fluid may exist as a plurality of discrete droplets surrounded by a continuous phase comprising a polymeric material. The fluid may be a liquid or a gas.

  The invention extends to an electro-optic display, front plane laminate, reverse front plane laminate or double release film comprising the electro-optic assembly of the invention.

  The invention also provides an electrophoretic medium comprising a continuous phase and a discontinuous phase, the discontinuous phase comprising a plurality of droplets, each of which is disposed within the suspension fluid and the suspension fluid; Including at least one particle capable of moving through the fluid after an electric field is applied to the electrophoretic medium, the continuous phase surrounding and encapsulating the discontinuous phase and having a molecular weight of less than about 3,500 An electrophoretic medium is provided that includes a polymeric binder that has been subjected to dialysis or diafiltration to remove organic species having the following: The electrophoretic medium may be either a capsule type or a polymer dispersion type, that is, there may or may not be a capsule wall between each droplet and the binder.

  The present invention also provides an electrophoretic medium comprising a continuous phase and a discontinuous phase, the discontinuous phase comprising a plurality of droplets, each of which is disposed within the suspension fluid, and the suspension fluid, Comprising at least one particle capable of moving through the fluid after application of an electric field to the electrophoretic medium, wherein the continuous phase surrounds and encapsulates the discontinuous phase, based on the weight of the electrophoretic medium There is provided an electrophoretic medium comprising a polymeric binder having a content of N-methylpyrrolidone not exceeding about 1,000 ppm.

  The invention extends to an electro-optic display, front plane laminate, inverted front plane laminate or double release film comprising the electro-optic assembly or electrophoretic medium of the invention.

The display of the present invention can be used in any application where prior art electro-optic displays have been used. Thus, for example, the display can be used in electronic book readers, portable computers, tablet computers, mobile phones, smart cards, signs, watches, shelf labels and flash drives.
For example, the present invention provides the following items.
(Item 1)
An electro-optic assembly comprising an adhesive layer and an electro-optic material layer, wherein the adhesive layer includes a polymer adhesive material and an ionic material, and the ionic material is fixed to the polymer adhesive material. Having one of a cation and an anion, and the other of the cation and anion that can move freely through the polymer adhesive material, the ionic material reduces the volume resistance of the polymer adhesive material; An electro-optic assembly that is not removed by heating the polymeric adhesive material to 50 ° C.
(Item 2)
The electro-optic assembly according to item 1, wherein the ionic material comprises a carboxylic acid anion and a quaternary ammonium or phosphonium cation immobilized on the polymeric adhesive material.
(Item 3)
The electro-optic assembly of claim 1, wherein the polymeric adhesive material comprises polyurethane.
(Item 4)
The electro-optic assembly of item 1, wherein the ionic material comprises a quaternary ammonium or phosphonium cation immobilized on the polymeric adhesive material, and a hexafluorophosphate, tetrabutyl borate or tetraphenyl borate anion.
(Item 5)
Item wherein the ionic material comprises a repeating unit derived from a basic monomer and a mobile anion selected from the group comprising sulfonate, sulfate, hexafluorophosphate, tetrafluoroborate, bis (methanesulfonyl) imidate, phosphate and phosphonate. The electro-optic assembly according to claim 1.
(Item 6)
The basic monomer is vinylpyridine, β-dimethylaminoethyl acrylate, N-methyl or benzyl (vinylpyridine), N-alkyl or alkaryl-N′-vinylimidazole, and β- (trimethylammonioethyl) acrylate or 6. The electro-optic assembly of item 5, comprising any one or more of methacrylates.
(Item 7)
The electro-optic assembly of claim 1, wherein the electro-optic material includes an electrophoretic material that is disposed in a fluid and includes a plurality of charged particles that can move through the fluid under the influence of an electric field.
(Item 8)
The electro-optic display according to item 7, wherein the fluid is a gas.
(Item 9)
An electro-optic display, front plane laminate, inverted front plane laminate or double release film comprising the electro-optic assembly of item 1.
(Item 10)
An electronic book reader, portable computer, tablet computer, mobile phone, smart card, sign, clock, shelf label or flash drive comprising the electro-optic display according to item 9.
(Item 11)
An electro-optic assembly comprising an adhesive layer and a layer of electro-optic material, wherein the adhesive layer is a polymer bond that has been subjected to dialysis or diafiltration to remove organic species having a molecular weight of less than about 3,500. An electro-optic assembly comprising an agent material.
(Item 12)
An electro-optic assembly comprising an adhesive layer and a layer of electro-optic material, wherein the adhesive layer has a N-methylpyrrolidone content not exceeding 500 ppm based on the total weight of the adhesive layer and the electro-optic material layer An electro-optic assembly comprising a polymer adhesive material having:
(Item 13)
13. The electro-optic assembly of item 12, wherein the polymer adhesive material comprises polyurethane.
(Item 14)
13. The electro-optic assembly according to item 12, having a content of N-methylpyrrolidone not exceeding 200 ppm.
(Item 15)
13. The electro-optic assembly of item 12, wherein the electro-optic material includes an electrophoretic material that is disposed in a fluid and includes a plurality of charged particles that can move through the fluid under the influence of an electric field.
(Item 16)
16. The electro-optic display according to item 15, wherein the fluid is a gas.
(Item 17)
13. An electro-optic display, front plane laminate, inverted front plane laminate or double release film comprising the electro-optic assembly according to item 12.
(Item 18)
An electronic book reader, portable computer, tablet computer, mobile phone, smart card, sign, clock, shelf label or flash drive comprising the electro-optic display according to item 17.
(Item 19)
An electrophoretic medium comprising a continuous phase and a non-continuous phase, wherein the non-continuous layer includes a plurality of droplets, each of which is disposed within the suspension fluid and the suspension fluid to the electrophoretic medium. Comprising at least one particle capable of moving through the fluid after application of an electric field, wherein the continuous phase surrounds and encapsulates the discontinuous layer to remove organic species having a molecular weight of less than 3,500 An electrophoretic medium comprising a polymeric binder that has been subjected to dialysis or diafiltration.
(Item 20)
An electrophoretic medium comprising a continuous phase and a non-continuous phase, wherein the non-continuous layer includes a plurality of droplets, each of which is disposed within the suspension fluid and the suspension fluid to the electrophoretic medium. Comprising at least one particle capable of moving through the fluid after application of an electric field, wherein the continuous phase surrounds and encapsulates the discontinuous layer and exceeds 1000 ppm based on the weight of the electrophoretic medium An electrophoretic medium comprising a polymer binder having a content of no N-methylpyrrolidone.

The only figure in the accompanying drawings is a graph showing optical state readings obtained in Example 5 below.

  As indicated above, the present invention has two main aspects, the first of which relates to the incorporation of non-diffusible ionic material into the adhesive layer, and the second of which is an electrophoretic medium and It relates to the use of dialysis or diafiltered adhesive materials and / or binders in displays. The two main aspects of the present invention are mainly discussed separately below, but it is readily apparent that both aspects of the present invention can be incorporated into a single physical display.

Part A: Non-diffusible ionic material As indicated above, in one aspect, the present invention provides an electro-optic assembly comprising an electro-optic layer and an adhesive layer. The adhesive layer includes an ionic material, one of which cannot move through the adhesive layer, but the other. This type of ionic material prevents ions from diffusing out of the adhesive layer and potentially damaging other layers (eg, organic semiconductor layers) into which ions diffuse.

  The ionic conduction of the polymer adhesive layer has been shown to occur by a “hopping” mechanism, where dissociated free ions migrate in ionic aggregates (ion pairs and higher aggregates). Most of these aggregates are neutral in nature. According to the present invention, only one of the anion and cation of the ionic material can move. Although fixed ions are constrained to one position, mobile ions can still move freely. An example of a suitable ionic material is a polymeric salt, such as an ionic salt of a polymeric carboxylic acid. In this case, the carboxylate ion is virtually immobile because it is bound to its polymer chain and can only move with the polymer as a whole. On the other hand, the cationic counter ion is free to participate in the hopping motion, and the speed at which it can move depends on the strength of the electrostatic interaction with the anionic carboxylic acid, the carboxylic acid-counter ion condensation in the adhesive medium. It depends on the concentration of the aggregate, the viscosity of the medium, and the free energy of solvation of the counter ion by the medium.

  As in the ion-doped adhesive described in the aforementioned US Pat. No. 7,012,735, in the present invention, large cations cause the electrostatic energy they have a relatively low attraction to ionic aggregation states. Therefore, it is advantageous in that it easily dissociates from them. As an example, quaternary ammonium hydroxide can be used to neutralize carboxylic acid functional groups on the polyurethane, resulting in a quaternary ammonium carboxylate polymer that can support ionic conduction as described above.

The ionic material is preferably selected such that the conductivity of the final adhesive layer after drying can be modified and adjusted by changing the carboxylic acid content of the polyurethane and also by the cations used. For example, in the aforementioned system where the carboxylic acid groups on the polyurethane are neutralized with quaternary ammonium hydroxide at a given carboxylic acid content, the conductivity is in the following order:
An increase in tetramethylammonium <tetraethylammonium <tetrabutylammonium is expected. Phosphonium salts can also be used and should be somewhat more conductive than nitrogen-containing analogs due to the relatively large size of the central atom. Other cationic species (eg, metal complex ions) may also be useful for this purpose. The solubility of the ionic material in the adhesive is not a problem in the present approach because the ions are an inherent part of the media and therefore cannot be phase separated as a separate crystalline phase.

As long as the acidic component of the polymer adhesive also has at least one dissociable proton present, the carboxylic acid component can be replaced with a group having a higher dissociation constant, such as sulfuric monoester, sulfonic acid, sulfinic acid, phosphonic acid, phosphine. It can also be made more acidic by replacement with acid groups or phosphate esters. Quaternary salts and other large cations are also expected to be most useful as counterions due to their large size and relatively high degree of ionic dissociation in low polarity dry adhesive media. Nitrogen-based acids can also be used when bound to a sufficiently electron-withdrawing functional group (eg, RSO ₂ —NH—SO ₂ R). In this case, working ions are present in protonated form even in the dry adhesive, so almost all mobile ions can be used, including tertiary ammonium. However, mobile ions based on relatively large amines (ie, those having relatively long alkyl tails) may still be preferred because the size of the ions is effectively larger and therefore the ion pairs containing them are more dissociable.

  Alternatively, the carboxylic acid group on the adhesive can be used with a mobile ion that is not a strong Bronsted acid, i.e., has no acidic protons such as the quaternary cations discussed above.

  The adhesive composition in which the cation is a fixed ion uses a quaternary ammonium group in the polymer main chain or as a side chain, preferably a large anion as a mobile ion (for example, hexafluorophosphate, tetrabutyl borate, tetraphenyl borate, etc. ). Quaternary ammonium groups can be replaced by phosphonium, sulfonium or other cationic groups that do not have dissociative hydrogen, including those formed by complexation with metal cations. Examples of the latter include polyether / lithium ion inclusion complexes, in particular cyclic polyethers with transition metal ions (eg 18-crown-6) or polyamine complexes. In this case, the anionic mobile ions can include stronger basic materials such as carboxylates or even phenolates in addition to the types of ions described above.

  Alternative fixed cationic adhesive materials include polymers containing repeat units derived from basic monomers such as poly (vinyl pyridine), poly (β-dimethylaminoethyl acrylate), and the like, and a good blend of Copolymers are included that include a mobile anion that is not a steadi acceptor (eg, sulfonate, sulfate, hexafluorophosphate, tetrafluoroborate, bis (methanesulfonyl) imidate, phosphate, phosphonate, etc.). Quaternary salts derived from such amino monomers, such as poly (N-methyl or benzyl (vinylpyridinium)), poly (N-alkyl (or alkaryl) -N′-vinylimidazolium), and poly (β- Trimethylammonioethyl) acrylate or methacrylate salts, as well as vinyl copolymers containing these ionic groups can also be used. As before, larger mobile ions are preferred.

  These chemical modification techniques are not limited to polyurethane, but can be applied to any polymer of suitable structure. For example, vinyl-based polymers can contain either anion-fixed ions or cation-fixed ions.

Part B: Dialyzed or diafiltered adhesive material and / or binder As already mentioned, in one aspect of the invention, in one aspect of the invention, the ion dopant from one adhesive layer to another in an electro-optic display The problems caused by migration are reduced or eliminated, especially damage to the active matrix backplane that includes transistors made from certain organic semiconductors. But now the cause of these problems is not limited to ionic dopants, but it can be transferred from adhesive layers or binder layers of electro-optic displays to other layers as well as ionic dopants. It has been found that other fugitive species present in the agent and binder compositions are included. One such fugitive species of particular importance is N-methylpyrrolidone (NMP), which is used as a solvent in the preparation of polyurethanes. Other fugitive species that may be important in some cases include other solvents used in the preparation of polyurethanes, and poorly characterized low molecular weight molecules derived from polymerization reactions. It has been found that removing NMP by careful drying from the adhesive layer improves the storage stability of the layer. Lamination adhesive dialysis removes both NMP and other low molecular weight materials and is even more effective. The non-diffusible ionic material adhesive composition of the present invention can be subjected to dialysis because electrical neutrality prevents the total separation of fixed and mobile ions, and after dialysis, the adhesive material becomes diffusible. Contains little or no material. Accordingly, it has been found that the present adhesive is particularly effective in reducing the detrimental effects of lamination adhesives on the performance of backplanes containing organic semiconductors. Diafiltration can be used instead of dialysis.

  As already mentioned, the non-diffusible ionic material adhesive material of the present invention can be purified by dialysis or diafiltration. However, it may also be useful to synthesize these adhesive materials by dialysis. For example, an aqueous solution of polyamine or polyether can be partially transformed into a cationic complex by dialysis of a polymer solution in a solution of a suitable water-soluble metal salt.

  Dialysis or diafiltration can also be used to remove NMP and other fugitive species from such adhesives before they are mixed with conventional ionic dopants. Thus, as already mentioned, in its second main aspect, the present invention provides an electro-optic assembly comprising an adhesive layer and an electro-optic material layer, wherein the adhesive layer is less than about 3,500. An electro-optic assembly is provided that includes a polymeric adhesive material that has been subjected to dialysis or diafiltration to remove organic species having a molecular weight. Such dialysis or diafiltration can be used, among other things, to remove NMP, tetrahydrofuran (THF) and acetone. Similarly, the second aspect of the invention also provides an electro-optic assembly comprising an adhesive layer and an electro-optic material layer, the adhesive layer comprising in all cases the adhesive layer and the electro-optic material layer. An electro-optic assembly is provided that includes a polymeric adhesive material having a N-methylpyrrolidone content of no more than about 500 ppm, preferably no more than about 200 ppm, and desirably no more than about 100 ppm, based on total weight.

  In a second aspect of the invention, there is also an electrophoretic medium comprising a continuous phase and a discontinuous phase, the discontinuous phase comprising a plurality of droplets, each of which is a suspension fluid, and the suspension stream Comprising at least one particle disposed within the body and capable of moving through the fluid after application of an electric field to the electrophoretic medium, the continuous phase surrounding and encapsulating the discontinuity; An electrophoretic medium is provided that includes a polymeric binder that has been subjected to dialysis or diafiltration to remove organic species having a molecular weight of less than 500. The electrophoretic medium may be either capsule type or polymer dispersed type, i.e., there may or may not be a capsule wall between each droplet and the binder. In a second aspect of the invention, there is also an electrophoretic medium comprising a continuous phase and a discontinuous phase, the discontinuous phase comprising a plurality of droplets, each of which is a suspension fluid, and the suspension stream Comprising at least one particle disposed within the body and capable of moving through the liquid after application of an electric field to the electrophoretic medium, the continuous phase surrounding and encapsulating the discontinuous phase, in all cases N-methylpyrrolidone, tetrahydrofuran, not exceeding about 1000 ppm, preferably not exceeding about 400 ppm, desirably not exceeding about 200 ppm, based on the weight of the electrophoresis medium (ie, the combination of the continuous and discontinuous phases) And an electrophoretic medium comprising a polymeric binder having a total content of acetone.

  As already indicated, the second aspect of the invention can be used to remove NMP and possibly other fugitive species from lamination adhesives and / or binders used in electro-optic displays. In many cases, removal of fugitive species from the binder is more important than removal from the lamination adhesive. The lamination adhesive layer is usually prepared by coating the release sheet with a flowable adhesive and then drying the adhesive layer so that the coherent layer of adhesive is released from the release sheet. The process formed on is included. High temperatures and low coating speeds during the drying process are sufficient to drive out large proportions of volatile organic species; for example, a laminating adhesive coated with 50,000 ppm NMP will yield only 200 ppm NMP after drying. It was found to have. In addition, the only layers present during drying are the lamination adhesive and release sheet (lamination of the adhesive to the electro-optic medium is performed only after the drying step), so the selection of drying conditions is lamination. It can be based solely on the properties of the adhesive itself, and need not take into account the properties of the electro-optic medium. In contrast, binders used in electrophoretic media are typically mixed with a discontinuous phase of the media to form a slurry that is then coated and dried to form the electrophoretic media. Thus, in this case, the drying conditions must take into account the characteristics of the discontinuous phase, and in particular the problems related to the simultaneous removal of volatile discontinuous phase solvents. Finally, from a quality control point of view, it is a good guarantee that removing all materials that can damage any backplane that can be expected to be in contact with the electro-optic medium, As a result, the number of unknown components (the concentration of which can vary without knowing or controlling) is kept to a minimum; obviously, as a matter of good manufacturing processes, the use of pure materials of known composition is highly desirable.

  Both dialysis and diafiltration are well known methods for purifying colloidal and polymer suspensions. In both techniques, this suspension is confined by a semipermeable membrane whose opposite side is a wash solution, usually water or a buffer solution. Molecules that can pass through the membrane and are soluble in the wash solution are equilibrated between the two regions of the device and removed from the suspension by exchange of the wash solution. Typically, the membrane is made of a material that allows selective passage of low molecular weight materials, and water is generally used as a solvent; in the present invention, a membrane having a molecular weight cutoff (MWCO) of about 3.5 kD. Found useful. Since NMP is a water soluble solvent, these techniques are well suited to remove this contamination. At the same time, other soluble materials, some having potentially harmful properties, can also be removed. As in the case of removal by drying, it is not necessary that the species being removed be appreciably volatile. By adjusting the properties of the membrane, the class of molecules removed can be changed. For example, in certain lamination adhesives or binders, the presence of water-soluble oligomeric polymer fragments is a problem and membranes with higher MWCO can be used to remove such fragments; Various semipermeable membranes with MWCO are commercially available.

  Either dialysis or diafiltration can be used in the present method, but diafiltration is usually preferred for commercial production. While dialysis is a simple equilibration process, diafiltration facilitates mass transport through the membrane using high flow conditions and high membrane permeation pressure. Diafiltration is substantially faster than dialysis and can be used under conditions that prevent dilution of the material to be purified, often as in dialysis. Diafiltration is an easily scalable process, and both laboratory and production scale equipment is available at a reasonable cost. Diafiltration is an established industrial procedure that is widely used in biochemistry and other industries.

  We have shown that both dialysis and diafiltration are effective in removing NMP from commercial polyurethane latex suspensions. It has been empirically found that dialysis and diafiltration of polyurethane latex using membranes with low MWCO (3.5 kD) can reduce NMP content by over an order of magnitude in a few hours. For example, the NMP content of certain polyuretan binders was reduced from about 14% (140,000 ppm) to about 500 ppm by diafiltration. When using dialysis, the efficiency of NMP removal could be limited by the dilution of the latex, which made it difficult to coat the latex, especially in the case of lamination adhesives. Latex can be concentrated by evaporation of excess water under reduced pressure, which is an inappropriate operation. Investigation of the molecular weight distribution of the purified polyurethane latex showed that it was essentially the same as its starting material, i.e. the polymer was not lost during dialysis. Many advantages have been seen when dialyzed material is used in place of undialyzed binders and lamination adhesives.

  First, the performance degradation of the organic semiconductor backplane has been greatly reduced. Similar results were obtained when only the binder was dialyzed rather than the lamination adhesive. However, when the dialysis of the binder was omitted, a significant decrease in the performance of the organic semiconductor device was observed.

  A second advantage was that the cell void resistance (a measure of the conductivity of the front plane laminate) was typically higher than about 50 percent using dialyzed material. Due to the higher cell void resistance, there is little requirement for the on-state conductivity of the working transistor (ie, a lower on / off ratio is allowed). This is a particularly important feature for organic semiconductor transistors whose on-off ratio is usually not as high as that of inorganic transistors.

A third advantage was a small improvement in the electro-optic properties of electrophoretic media made from dialyzed latex. As illustrated in Example 5 below, the use of dialyzed polyurethane latex is about 2 L in dynamic range (difference between extreme white and dark electro-optic states of the medium) compared to the use of undialyzed material. ^* Provided an improvement (using the normal CIE definition of L ^* ).

  In order to illustrate details of the preferred reagents, conditions and techniques used in the present invention, the following examples are now given, which are intended to be illustrative only.

Example 1
Synthesis of TMXDI-PPO polyurethane by neutralization with tetrabutylammonium hydroxide The polyurethane prepared in this example is similar to the prior art polyurethane produced in Example 2 below, except that it has a higher acid content. .

The prepolymer was prepared in a three-necked round bottom flask equipped with a magnetic stirrer, condenser and nitrogen inlet. The reaction was performed under nitrogen. Tetramethylxylene diisocyanate (TMXDI, supplied from Aldrich Chemical Company, 16.34 g, 0.067 mol), poly (propylene glycol) diol (supplied from Aldrich Chemical Company, average _Mn about 2000, 33.5 g, 0.0168 mol ), And dibutyltin dilaurate (supplied by Aldrich Chemical Company, 0.04 g) were placed in the flask and the mixture was heated in an oil bath at 90 ° C. for 2 hours. Thereafter, a solution of 2,2-bis (hydroxymethyl) propionic acid (Aldrich, 3.35 g, 0.025 mol) in 1-methyl-2-pyrrolidinone (Aldrich, 8.5 g) was added to the flask, The reaction was allowed to proceed for an additional 2 hours at 90 ° C. to obtain an NCO-terminated prepolymer. The temperature of the reaction mixture was then lowered to 70 ° C. Separately, tetrabutylammonium hydroxide (NBu ₄ OH) (Aldrich, 6.15 g, 0.0237 mol) and deionized water (100 g) were jacketed with a mechanical stirrer, thermometer and nitrogen inlet In a 500 mL glass reactor and the resulting mixture was heated to 35 ° C. under nitrogen. The prepolymer mixture was then slowly added to the aqueous NBu ₄ OH solution and the prepolymer was converted to an aqueous dispersion under mechanical stirring and a nitrogen atmosphere. After this dispersion step, the chain extension reaction was performed at 35 ° C. with hexamethylenediamine (manufactured by Aldrich) dissolved in a small amount of water. The end point of the chain extension reaction was determined from pH measurements. Finally, the obtained dispersion was heated to 50 ° C. for 1 hour, and it was confirmed that all residual isocyanate groups were consumed by water.

(Example 2)
Synthesis of TMXDI-PPO polyurethane by neutralization with triethylamine (control)
Example 1 was repeated until the NCO-terminated prepolymer was obtained, and the temperature of the reaction mixture was lowered to 70 ° C. Then, triethylamine (manufactured by Aldrich, 2.4 g, 0.0237 mol) was slowly added over a period of 30 minutes to neutralize the carboxylic acid. The reaction mixture was then slowly added to deionized water (100 g) at 35 ° C. in a jacketed 500 mL glass reactor under mechanical stirring and nitrogen atmosphere to convert the prepolymer to an aqueous dispersion. The chain extension reaction and the final heating of the dispersion to 50 ° C. were carried out in the same manner as in Example 1.

Example 3
Example 1 Preparation of Experimental Single Pixel Display from Materials Prepared in Example 1 and Example 2 Polyurethanes prepared in Example 1 and Example 2 above were separately applied to a plated release film with a (dry) thickness of about 20 μm. Coated. The coated polymer film is dried in a belt-type drying oven at 60 ° C. and a transfer rate of 1 ft / min (about 5.1 mm / sec); these conditions reduce the NMP content to a very low concentration Is known. Separately, an electrophoretic medium was prepared substantially as described in Example 4 of US Pat. No. 7,002,728 and coated on one surface with indium tin oxide (ITO). A 5 mil (127 μm) poly (ethylene terephthalate) (PET) film was coated on the ITO coated surface. The two subassemblies were laminated together with an electrophoretic layer in contact with a lamination adhesive to form a front plane laminate as described in the aforementioned US Pat. No. 6,982,178. The release sheet is peeled from the front plane laminate, and the remaining layers are laminated to an experimental single pixel 2 inch (51 mm) square backplane containing a layer of carbon black on a PET film to create an experimental single pixel display. Formed. No added dopant was incorporated into any adhesive coating. This experimental display was conditioned for one day at 50 percent relative humidity (as discussed in several aforementioned E Ink patents and applications, the electro-optical properties of the electrophoretic display vary with the amount of moisture in the electrophoretic layer. Therefore, it is desirable to adjust the specimen under standard conditions before testing).

The experimental displays are then driven to their black and white optical states using 250 millisecond pulses at various voltages, the reflectivities of the black and white optical states are measured, and these reflectivities are expressed as L ^* Is the usual CIE definition:
L ^* = 116 (R / R ₀ ) ^1/3 −16
(Where R is the reflectivity and R ₀ is the standard reflectivity value)
The electro-optical properties of the experimental display were tested by converting to a conventional L ^* value with Table 1 below shows the dynamic range (difference between L ^* values for the black and white optical states) obtained at various voltages:

表１から、本発明のラミネーション用接着剤が対照接着剤に比べて全ての駆動電圧で実質的により大きなダイナミックレンジを示したことがわかる。この改善は、導電性の差から予想されるものと一致し、低酸分の従来技術のドープ接着剤を用いて見られるものと同様である。トリエチルアミンで中和した対照接着剤は、非常に抵抗性であるラミネーション用接着剤に対して予想された電気光学応答を示す。操作中のディスプレイの目視検査により、対照接着剤を用いたディスプレイはディスプレイの端部に少量のブルーミングのみを示し、一方本発明の接着剤を用いるディスプレイは、大量のブルーミングを示すことがわかった。高度のブルーミングはまた、高導電性の接着剤と一致する。

From Table 1, it can be seen that the lamination adhesive of the present invention exhibited a substantially greater dynamic range at all drive voltages compared to the control adhesive. This improvement is consistent with that expected from the conductivity differences and is similar to that seen using prior art doped adhesives with low acid content. A control adhesive neutralized with triethylamine shows the expected electro-optic response to a lamination adhesive that is very resistant. Visual inspection of the display during operation showed that the display with the control adhesive showed only a small amount of blooming at the edges of the display, while the display with the adhesive of the present invention showed a large amount of blooming. High blooming is also consistent with highly conductive adhesives.

  The experimental display was also subjected to a cryogenic test. As discussed in some of the aforementioned E Ink patents and applications, the electro-optic performance of electrophoretic displays declines sharply at low temperatures, at least in part, because the conductivity of lamination adhesives decreases with temperature. Tend to. To determine the low temperature behavior of the experimental display of the present invention, the display is driven at a temperature of +25 to -25 ° C. using a 15V pulse of either 250 or 500 milliseconds duration and the end of the drive pulse 2 The dynamic range was determined using the reflectance taken after minutes. (This two-minute break before taking the reflectance value allows for some kind of short-term effect that affects the reflectance value to dissipate). The obtained reflectance values were converted to dynamic range values as before, and the results are shown in Table 2 below.

表２のデータから、パルス長補償が用いられることを条件として、すなわち、駆動パルスを低温で長くすることを条件として、本発明の接着剤は、約−１０℃まで下がって適切な性能を与えることがわかる。この低温性能は、高度にドーピングした従来技術のラミネーション用接着剤のものに匹敵する。

From the data in Table 2, provided that pulse length compensation is used, i.e., if the drive pulse is lengthened at low temperatures, the adhesive of the present invention drops to about -10 <0> C to provide adequate performance. I understand that. This low temperature performance is comparable to that of highly doped prior art lamination adhesives.

Example 4
Purification of Lamination Adhesive of the Present Invention by Dialysis A sample of the lamination adhesive (49.3 g, 35 wt% solids) prepared in Example 1 above was applied to a dialysis membrane tube (Fisher® regenerated cellulose membrane, MWCO 3500). After closing both ends of the tubing with clamps, the tubing was immersed for about 4 hours in a stirred tank of continuously replenished water. At the end of this time, 61.6 g of material with a solids content of 29.5% (95% recovery) was then recovered. Initially, the NMP content was 4.4%; after dialysis, the content was 1.4%. This NMP content can be used as an alternative to the removal of other water soluble low molecular weight materials.

  Preliminary long-term storage tests for displays using the dialysis lamination adhesive prepared in Example 4 above, and a proprietary organic semiconductor backplane, together with both dialysis or non-dialysis prior art lamination adhesives, The inventive dialysis lamination adhesive has been shown to have substantially better long-term storage properties than prior art adhesives.

(Example 5)
Use of dialyzed binders and lamination adhesives in electrophoretic displays Polyurethane latex was synthesized substantially as described in Example 2 of US 2008/0074730 and described below. Used as experimental binder. A second polyurethane latex was synthesized substantially as described in Example 2 of US Patent Application No. 2005/0107564 and used as a laminating adhesive in these experiments.

An experimental single pixel display is prepared substantially as described in Example 7 of US Pat. No. 7,002,728 except that the binder and lamination adhesive described above are used; The adhesive was doped with 180 ppm tetrabutylammonium hexafluorophosphate. Four sets of experimental displays were made as follows:
(A) Neither binder nor lamination adhesive was dialyzed;
(B) The binder was dialyzed substantially as described in Example 4 above, but the lamination adhesive was not dialyzed;
(C) The binder was not dialyzed, but the lamination adhesive was dialyzed substantially as described in Example 4 above;
(D) Both the binder and the lamination adhesive were dialyzed substantially as described in Example 4 above.

The electro-optical properties of the four sets of experimental displays were then substantially described in Example 7 of US Pat. No. 7,002,728, except that a ± 15 V 300 millisecond pulse was used. And measured the reflectivity in the extreme white and dark states and converted to CIE L ^* units. The results are shown in the sole figure of the accompanying drawings. In each set of readings, the left bar represents the extreme white state of the display, the center bar represents the extreme dark state, and the right bar represents the dynamic range (ie, the extreme white and dark state, measured in L ^* units). Difference).

From this figure, it can be seen that dialysis of the binder and lamination adhesive did not adversely affect the electro-optic properties of the display. In fact, the two displays (B and D) where the binder was dialyzed showed an improved white state, and displays C and D showed an improved dark state (the dark state improvement was naturally better than Represented by a low L ^* value). Display D, where both binder and lamination adhesive were dialyzed, showed the maximum dynamic range in the four sets of displays.

  The electro-optic test was repeated using ± 15 V pulses of 100 and 500 ms duration and ± 10 V, 100, 300 and 500 ms pulses. In all cases, the results obtained were consistent with those shown in the figure.

  When the front plane laminate including the combination of the binder and the lamination adhesive described under (A) to (D) above is laminated on the back plane using the organic transistor, the front plane laminate including the non-dialysis binder is It was observed that it caused rapid degradation of the organic transistor, but not the front plane laminate containing the dialysis binder. A similar but smaller effect was observed with dialysis lamination adhesive.

  From the above, the present invention avoids the use of fugitive ionic species that can damage certain backplanes and potentially cause other problems, while at the same time electro-optical properties and low temperature performance comparable to that of prior art adhesives. It can be seen that a lamination adhesive can be provided. Furthermore, the present invention can be provided.

Claims (5)

  An electro-optic assembly comprising an adhesive layer and an electro-optic material layer, wherein the adhesive layer includes a polymer adhesive material and an ionic material, and the ionic material is chemically bonded to the polymer adhesive material One of its cations and anions and the other of its cations and anions that are free to move through the polymer adhesive material, the ionic material having a volume resistance of the polymer adhesive material And is not removed by heating the polymer adhesive material to 50 ° C., the ionic material contains quaternary ammonium or phosphonium cations, and carboxylate anions chemically bonded to the polymer adhesive material. The polymeric adhesive material comprises polyurethane, and the ionic material comprises a tertiary alloy. It does not contain emissions, electro-optical assembly.   The electro-optic assembly of claim 1, wherein the electro-optic material includes an electrophoretic material that is disposed in a fluid and includes a plurality of charged particles that can move through the fluid under the influence of an electric field. The electro-optic assembly according to claim 2, wherein the fluid is a gas. Electro comprising an optical assembly, an electro-optic display, front plane laminate ne over preparative, inverted front plane laminate or double release film of claim 1.   An electronic book reader, portable computer, tablet computer, mobile phone, smart card, sign, clock, shelf label or flash drive comprising the electro-optic display according to claim 4.

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